A Question

I've been neglecting my posting duties for a bit (I'm sorry!), so I thought I'd ask a simple question:

A patient, known to have condition "A", presents with a new complaint. The complaint isn't typically associated with condition "A". Is the patient more likely to have:

• a rare manifestation of condition "A", or
• a common manifestation of a second condition ("B")?

What do you think?

Note: It actually is possible to give an answer to this question, and the solution is ingenious.

I'll answer it next.